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    <script>
        /* 
            九九乘法表:使用双重for循环 结合正三角

            *
            **
            ***
            ****

            i    num(j 的最大值)
            0     1
            1     2
            2     3
            
            i + 1 = num
       */
        for (let i = 1; i < 10; i++) { //
            let str = '';
            for (let k = 1; k < i + 1; k++) {
                str = str + (k + '*' + i + '=' + i* k+ '  ');
            }
            console.log(str);
        }
    </script>
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